In the freight industry it is common to transport goods and other materials across international borders. This may be achieved by way of sea, land, or air, with suitable freight containers. There is a need for biosecurity when freighting goods and other materials internationally, i.e. in order to prevent or minimise the risk of insects, animals, or other living organisms undesirably transferring from one country to another. It is accordingly an object of at least one form of the present invention to go at least some way towards addressing the need for biosecurity within the freight industry, or alternatively to provide the public with a useful choice.